Class LinearGeometryBuilder

1	/*
2	* Copyright (c) 2016 Vivid Solutions.
3	*
4	* All rights reserved. This program and the accompanying materials
5	* are made available under the terms of the Eclipse Public License 2.0
6	* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
7	* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
8	* and the Eclipse Distribution License is available at
9	*
10	* http://www.eclipse.org/org/documents/edl-v10.php.
11	*/
12
13	package org.locationtech.jts.linearref;
14
15	import java.util.ArrayList;
16	import java.util.List;
17
18	import org.locationtech.jts.geom.Coordinate;
19	import org.locationtech.jts.geom.CoordinateList;
20	import org.locationtech.jts.geom.Geometry;
21	import org.locationtech.jts.geom.GeometryFactory;
22	import org.locationtech.jts.geom.LineString;
23	import org.locationtech.jts.geom.MultiLineString;
24
25	/**
26	* Builds a linear geometry ({@link LineString} or {@link MultiLineString})
27	* incrementally (point-by-point).
28	*
29	* @version 1.7
30	*/
31	public class LinearGeometryBuilder
32	{
33	private GeometryFactory geomFact;
34	private List lines = new ArrayList();
35	private CoordinateList coordList = null;
36
37	private boolean ignoreInvalidLines = false;
38	private boolean fixInvalidLines = false;
39
40	private Coordinate lastPt = null;
41
42	public LinearGeometryBuilder(GeometryFactory geomFact) {
43	this.geomFact = geomFact;
44	}
45
46	/**
47	* Allows invalid lines to be ignored rather than causing Exceptions.
48	* An invalid line is one which has only one unique point.
49	*
50	* @param ignoreInvalidLines <code>true</code> if short lines are to be ignored
51	*/
52	public void setIgnoreInvalidLines(boolean ignoreInvalidLines)
53	{
54	this.ignoreInvalidLines = ignoreInvalidLines;
55	}
56
57	/**
58	* Allows invalid lines to be ignored rather than causing Exceptions.
59	* An invalid line is one which has only one unique point.
60	*
61	* @param fixInvalidLines <code>true</code> if short lines are to be ignored
62	*/
63	public void setFixInvalidLines(boolean fixInvalidLines)
64	{
65	this.fixInvalidLines = fixInvalidLines;
66	}
67
68	/**
69	* Adds a point to the current line.
70	*
71	* @param pt the Coordinate to add
72	*/
73	public void add(Coordinate pt)
74	{
75	add(pt, true);
76	}
77
78	/**
79	* Adds a point to the current line.
80	*
81	* @param pt the Coordinate to add
82	*/
83	public void add(Coordinate pt, boolean allowRepeatedPoints)
84	{
85	if (coordList == null)
86	coordList = new CoordinateList();
87	coordList.add(pt, allowRepeatedPoints);
88	lastPt = pt;
89	}
90
91	public Coordinate getLastCoordinate() { return lastPt; }
92
93	/**
94	* Terminate the current LineString.
95	*/
96	public void endLine()
97	{
98	if (coordList == null) {
99	return;
100	}
101	if (ignoreInvalidLines && coordList.size() < 2) {
102	coordList = null;
103	return;
104	}
105	Coordinate[] rawPts = coordList.toCoordinateArray();
106	Coordinate[] pts = rawPts;
107	if (fixInvalidLines)
108	pts = validCoordinateSequence(rawPts);
109
110	coordList = null;
111	LineString line = null;
112	try {
113	line = geomFact.createLineString(pts);
114	}
115	catch (IllegalArgumentException ex) {
116	// exception is due to too few points in line.
117	// only propagate if not ignoring short lines
118	if (! ignoreInvalidLines)
119	throw ex;
120	}
121
122	if (line != null) lines.add(line);
123	}
124
125	private Coordinate[] validCoordinateSequence(Coordinate[] pts)
126	{
127	if (pts.length >= 2) return pts;
128	Coordinate[] validPts = new Coordinate[] { pts[0], pts[0]};
129	return validPts;
130	}
131
132	public Geometry getGeometry()
133	{
134	// end last line in case it was not done by user
135	endLine();
136	return geomFact.buildGeometry(lines);
137	}
138	}
139